The present invention relates to a semiconductor device and for example a semiconductor device containing a capacitive touch sensor circuit.
Capacitive touch sensor circuits are commonly utilized in the touch key and touch screen technical field. U.S. Pat. No. 8,089,289 discloses a structure for modulating a signal output from the switching capacitance circuit into a digital signal by using a sigma-delta modulator circuit. U.S. Pat. No. 7,312,616 discloses a structure that measures the value of a target measurement capacitance by comparing on a comparator, a reference voltage with a terminal voltage for a target measurement capacitance that is repeatedly charged and discharged at a specified frequency. Japanese Unexamined Patent Application Publication No. 2008-199408 discloses an oscillator whose frequency changes by touching or non-touching from an operating section and a structure for detecting a change in frequency of frequency signals output by the oscillator.